A fiber-reinforced composite material is a high-performance material that is enhanced in strength by impregnating high-strength fiber such as glass fiber, carbon fiber, aramid, or Kevlar in a polymer matrix material such as plastic or epoxy.
The fiber-reinforced composite material is advantageous in a reduction in weight and an increase in strength, but is disadvantageous in that a realizable shape is limited, so that the freedom of design is low.
For example, a bumper back-beam made of a general plastic material is more excellent in freedom of design, is lighter in weight, and is lower in cost than a metal material. However, the bumper back-beam made of the plastic material is lower in rigidity, so that crashworthiness is insufficient.
Meanwhile, if the bumper back-beam is made of a fiber-reinforced composite material, a high rigidity is obtained, so that crashworthiness is enhanced. However, the bumper back-beam made of the fiber-reinforced composite material is problematic in that the freedom of design is limited, so that it is difficult to manufacture the bumper back-beam as a single product. Thus, since some components should be separately formed and then assembled with each other, this leads to an increase in cost and an insufficient weight-lightening effect.
The present invention is intended to provide an insert injection molding method using a fiber-reinforced composite material, which employs the fiber-reinforced composite material as an insert, thus being high in freedom of design, increasing a strength, and reducing a weight, and an injection molded product using the method.